Teenage drivers have the highest proportion of cellphone-related crashes, and traffic crashes are their leading cause of death. The death rate among drivers age 14-17 years hiked 17% from 2014 to 2016 nationally, with increasing cellphone-related distracted-driving as a suggested contributor. While 40 states and DC had enacted young-driver phone laws to ban all cellphone use or handheld use by September 2017, provisions vary greatly (e.g., all cellphone ban vs. handheld phone ban, all license types vs. learner permits/intermediate licenses). The extent to which young-driver phone bans and their specific provisions reduce texting and crashes is unknown. Therefore, we propose a four-year project with objectives to determine, across multiple states, the impact of young-driver phone bans and universal phone bans (i.e., for all ages) on texting or emailing while driving, and the rates of injury and fatal crashes among teens (<18 years). We hypothesize that the effectiveness of laws is impacted by certain provisions. The specific aims of this renewal application are to determine which provisions of young-driver phone bans and universal texting bans reduce teen texting or emailing while driving (Aim 1), and to identify which provisions of young-driver phone bans and universal phone bans reduce crashes involving teen drivers (<18 years) (Aim 2). Cellphone ban provisions to be examined include: 1) scope of banned activities (texting, handheld phone use, all phone use); 2) affected license types (learner permit / intermediate license, all licenses); 3) mode of enforcement (primary enforcement?officers can stop a vehicle for phone use only; or secondary enforcement?driver must first be cited for another infraction); 4) initial monetary amount of fine; 5) increases in fines for multiple citations; and 6) whether an infraction delays full licensure. The aims will be accomplished by combining and analyzing survey, legislative, economic, population, and crash data from various systems maintained by federal, state, and private agencies. Random-effects logistic and quasi-Poisson models will be used to estimate the effects of state-level laws on individual-level phone use and state-level crash rates. Level of enforcement will be examined as a mediator in the path from cellphone laws to changes in cellphone-use-while-driving behaviors, as well as changes in injuries, and deaths related to cellphone use while driving. Guided by strong preliminary data and our last R01, this study is also innovative by using multiple measures of impact include texting while driving, fatal crashes, and driver injuries. This project is significant, because its findings can inform states' efforts to develop/improve laws to reduce phone-related crashes, injuries, and deaths involving teen drivers.